src/cmd/cos_kernel_args/cmd_show.go

// Copyright 2026 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"context"
	"flag"
	"fmt"

	"github.com/google/subcommands"

	"cos.googlesource.com/cos/tools.git/src/pkg/cosboot"
)

type showCmd struct{}

func (*showCmd) Name() string {
	return "show"
}

func (*showCmd) Synopsis() string {
	return "Show kernel arguments that will be used on the next boot."
}

func (*showCmd) Usage() string {
	return "show [disk image]\n"
}

func (*showCmd) SetFlags(f *flag.FlagSet) {}

func (*showCmd) showForGRUBBoot(disk string) subcommands.ExitStatus {
	cmdLine, err := cosboot.NextGRUBCmdLine(disk)
	if err != nil {
		fmt.Printf("Error reading next GRUB command line: %v", err)
		return subcommands.ExitFailure
	}
	fmt.Println(cmdLine)
	return subcommands.ExitSuccess
}

func (*showCmd) showForUKIBoot() subcommands.ExitStatus {
	return subcommands.ExitSuccess
}

func (c *showCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}) subcommands.ExitStatus {
	disk := ""
	if f.NArg() > 0 {
		disk = f.Arg(0)
	}

	bootPath, err := cosboot.DiskBootPath(disk)
	if err != nil {
		fmt.Printf("Error identifying boot path: %v\n", err)
		return subcommands.ExitFailure
	}

	if bootPath == cosboot.GRUBBoot {
		return c.showForGRUBBoot(disk)
	} else if bootPath == cosboot.UKI {
		return c.showForUKIBoot()
	} else {
		// This should never happen
		fmt.Println("Could not identify boot path")
		return subcommands.ExitFailure
	}
}